低渗透非达西气体渗流模型及计算方法

在一系列假定条件下，建立了一个低渗透非达西气体渗流的非线性移动边界偏微分方程数学模型，在理论上论证模型解的存在唯一性基础上，用对数网格对求解区域进行剖分，建立显式预测隐式校正格式，进而讨论模型的算法。此模型和算法具有一定的应用价值。     

套管水泥环刚度与强度对抗挤性能影响分析

油气井固井水泥环的作用就是减小和改善套管的受力状况，延长套管的使用寿命。套管水泥环组合体在一定的外挤压力作用下，均有可能进入屈服状态或发生强度破坏，而水泥环弹性模量、泊松比及其几何参数均表现为组合体刚度对抗挤性能的影响，所以在套管抗挤性能分析中，应该同时考虑组合体刚度以及套管、水泥环的强度对组合体抗挤性能的影响。文章根据厚壁筒弹塑性力学理论，建立了组合体刚度以及套管、水泥环强度对抗挤性能影响的控制方程，揭示了套管、水泥环强度及组合体刚度对抗挤性能的影响规律，得到套管水泥环组合体抗挤性能控制图。在均匀外挤压力作用下，套管、水泥环的强度将确定组合体抗挤性能的刚度控制区，在组合体刚度控制区内，水泥环对套管抗挤强度的提高程度取决于组合体刚度控制线斜率，在套管钢级和壁厚一定条件下，提高水泥环材料弹性模量，增大组合体刚度控制线斜率，可以提高套管水泥环组合体的抗挤性能。     

塑料颜料的性能及在涂布纸中的应用

主要对塑料颜料的生产方法、运输和存储、输送、化学物理性质、作用机理等方面进行了阐述，并对今后塑料颜料的运用进行了展望。     

前馈系统中辅助放大器非线性分析

前馈系统中由于信号对消环路失配,导致在辅助功放输入端载波信号无法完全对消,辅助放大器的再次非线性失真会影响整个系统的失真。本文研究了残余载波信号再次产生的互调失真对整个系统线性化指标的影响,并给出了系统性能与电路参数和幅度、相位失配的关系式,通过这个关系式可以计算出要达到特定载波互调比时所需器件的最低指标要求。     

A note on oscillation criteria of second order nonlinear neutral delay differential equations

In recent years, many results on oscillation criteria of second order nonlinear neutral delay differential equations have been obtained, but some of these criteria are incorrect due to a mistake in a crucial auxiliary result. This note examines several of these results, provides some counterexamples and points out what causes the problems.     

几种高层建筑结构简化分析统一的连续-离散化方法

提出几种高层建筑结构简化分析统一的连续-离散化方法,即先将几种高层建筑结构连续化处理以后,均采用等效柱计算模型,再用矩阵位移法分析.几种结构等效柱的单元刚度矩阵具有同一形式,使计算和程序设计简便,用本文的方法可以分析变刚度高层框架、框-剪和剪力墙结构.     

Irrigation Hydrology: Crossing Scales

Hydrology is the science concerned with distribution, circulation, and properties of water of the earth and its atmosphere, across the full range of time and space scales. Subject matter ranges widely from chemical and physical properties to the relation of water to living things. Irrigation hydrology is constrained to analysis of irrigated ecosystems in which water storage, applications, or drainage volumes are artificially controlled in the landscape and the spatial domain of processes varies from micrometers to tens of kilometers while the temporal domain spans from seconds to centuries. The continuum science of irrigation hydrology includes the surface, subsurface (unsaturated and groundwater systems), atmospheric, and plant subsystems. How do we scale up highly nonlinear physical, chemical, and biological processes understood at natural scales to macro- and mega-scales at which we measure and manage irrigated agroecosystems? How do we measure, characterize, and include natural heterogeneity in scaling nonlinear processes? In this paper, we discuss scaling issues and related research opportunities in irrigation hydrology with the hope of helping the irrigation-drainage engineering/science profession better address scaling problems in formulating designs affecting irrigated ecosystems.     

二次转速调节静态神经网络非线性控制策略研究

本文针对二次转速调节系统的阻尼小、精度低和开环不稳定等实际情况，介绍了一种静态神经网络非线性控制策略，并对所组成的控制系统进行了数字仿真研究，给出了有价值的结论。     

A generalized variational model of magneto-thermo- elasticity for nonlinearly magnetized ferroelastic bodies

Based on a generalized variational principle of total energy functional, this paper presents a theoretical model to describe the magneto-thermo-elastic interaction of soft ferroelastic bodies with nonlinear magnetization under stationary thermal and magnetic fields. The energy functional of the magneto-thermo-elastic system is established by the summation of energy of sub-systems of nonlinearly magnetized magnetic field, thermal field, and mechanical deformation. By means of the manipulation of the mixed variational principle with independent variations of magnetic scalar potential, displacement vector, and temperature, all governing equations, which are nonlinear and coupling among magnetic, elastic and thermal fields, together with the expressions of magnetic forces are obtained from the variational approach. In order to valuate the obtained model, some existing models of the magneto-elasticity and the thermo-elasticity, which are validly demonstrated in literature, as special cases of the problem considered here are deduced out from the general case. Finally, an analytical analysis of magneto-thermo-elastic instability is conducted to a simply supported ferromagnetic rectangular thin plate under both a uniform distribution of temperature and a uniform transverse magnetic field by means of the linearized theory and the perturbation technique.     

Innovative light metals: metal matrix composites and foamed aluminium

Low weight is required especially for those means of transport, in which material properties have to be evaluated with respect to their specific mass. The possibility of increasing the specific properties of recyclable light metals are described: reinforcements by ceramic particulates, by continuous ceramic or carbon fibres, or by the reduction of weight by foaming the metal. Examples of castings, extrusions and forgings of particulate reinforced (<30 vol.%) aluminium alloys are given and their advantages including stiffness and wear resistance are presented. The technique of selective reinforcements by co-extrusion of particulate reinforced alloys together with conventional alloys is described. High volume fractions (>40 vol.%) of reinforcements can be produced by gas pressure infiltration of either particulate or fibre preforms. In the case of aluminium matrix, the specific strength can be increased by a factor of up to 15, and the specific stiffness by a factor of up to 7, whereas for carbon fibre reinforced magnesium the specific strength can be increased even more. The anisotropy of fibre reinforced metal matrix composites is discussed as well as the possibilities to use cross ply preforms. The technique of foaming aluminium alloys yields materials with a specific mass in the range of 0.3–1.0 g/cm³. Such structures with essentially closed pores exhibit higher specific stiffness for beams and membranes than massive metal. The measurement and definition of stiffness and strength values appropriate for aluminium foams are presented by referring to compression tests.